What is the primary function of the lens in vision?

What is the primary function of the lens in vision?

• A. Focuses light onto the retina
• B. Controls the amount of light entering the eye
• C. Produces tears
• D. Filters ultraviolet light

Answer: (A)

The lens’s job is to focus light onto the retina by changing its shape to adjust the focal length as you look at objects at different distances. The cornea does most of the bending, but the lens fine-tunes the focus so light from distances ranging from near to far lands precisely on the retina, producing a sharp image. When you view something far away, the lens becomes flatter; for nearby objects, it thickens to increase refraction through accommodation. The other functions listed are handled by different parts: the iris and pupil regulate how much light enters, tears are produced to keep the eye moist, and UV protection comes mainly from the cornea and lens rather than being the primary purpose of the lens.

The lens’s job is to focus light onto the retina by changing its shape to adjust the focal length as you look at objects at different distances. The cornea does most of the bending, but the lens fine-tunes the focus so light from distances ranging from near to far lands precisely on the retina, producing a sharp image. When you view something far away, the lens becomes flatter; for nearby objects, it thickens to increase refraction through accommodation. The other functions listed are handled by different parts: the iris and pupil regulate how much light enters, tears are produced to keep the eye moist, and UV protection comes mainly from the cornea and lens rather than being the primary purpose of the lens.